The present invention is directed to railroad couplings, and more particularly concerns a hoist and related apparatus for facilitating and assisting in the replacement or placement of a knuckle in the coupling head of a drawbar.
Conventional railroad couplings or couplers for joining railroad cars one to another to form a train include opposing interlocking knuckles which are pivotally supported in respective coupling heads of opposing drawbars by knuckle or pivot pins. The knuckle pins are received in aligned openings in the knuckles and coupling heads of the drawbars with the openings having substantially vertical longitudinal axes which are offset from the center lines of the drawbars. The drawbars have neck or shank portions which are mounted in end sills of the railroad cars in a manner allowing the drawbars to slide into the end sill until a buffing surface of a raised portion or horn of the drawbar strikes a coupler striker on the exterior of the end sill. Typically the coupler shank is operably connected to the center sill of the car body through a conventional draft gear mechanism for standard draft gear cushioning of coupler impacts applied to the coupler and to provide for relative movement between the adjacent railroad cars. Conventional AAR F or E type railroad couplings are described, for example, in U.S. Pat. Nos. 4,079,842 and 4,640,422.
The interlocking knuckles of a conventional railroad coupling can be either in compression or tension, depending on the direction of movement of the train. When movement of the train reverses, and the knuckles change from a tension condition to a compression condition, the nose of each knuckle tends to slam into the throat portion of the other. After a period of time, this results in a metal fatigue condition with attendant cracks in the throat region of the knuckle. Complex and repetitive stress loadings on the coupling, particularly the knuckles and knuckle pins thereof, cause fatigue fracturing due to bending loads imposed upon movement of a train from a stopped condition as well as when the train reverses direction from a buff condition to a draft condition. Other conditions, such as rough terrain, worn railroad tracks, excessive weight due to heavy loads or especially lone trains, rocking or rolling of the railroad care, and rotation of the railroad cars for dumping while coupled to other cars by interlocking couplers constructed to accommodate rotary movement between the cars, brine about repetitive or excessive static or dynamic stress loadings on the knuckles and the knuckle pins. These conditions lead to failure of the knuckle pins and the knuckles.
Broken knuckle pins and knuckles of conventional railroad couplings lead to train separations, that is the separation of adjacent railroad cars in a train. In a six month study of train separations, it was found that broken knuckles caused almost 70% of train separations. When a train separates due to either a broken knuckle pin or knuckle, the train must be halted and the broken coupling element must be replaced so that the railroad cars can be reconnected one to another. The replacement of a knuckle in the field entails placement of a replacement knuckle and pin adjacent the separated railroad cars, the lifting of the heavy replacement knuckle (weighing about 80 pounds) up into position in the coupling head of a drawbar, placement of a knuckle pin in the coaxially aligned knuckle pin receiving openings of the coupling head and knuckle, insertion of a knuckle pin retaining key, followed by recoupling of the separated railroad cars by interlocking adjacent knuckles of the railroad coupling.
Replacement of a knuckle by a single trainman (brakeman, engineer, conductor) is difficult and dangerous due to the size and weight of the knuckle. Current railway procedures require that a train having only a single trainman (conductor) wait for additional assistance before attempting to manually replace a knuckle in the field. This downtime due to train separation may be quite lengthy as the required assistance may be hours away. A lengthy delay can cause a train to "go dead" and require a replacement or relief crew, rerouting of other trains, and train scheduling problems. Attempts at replacing knuckles by a single trainman can lead to physical injury and temporary or permanent disability of the trainman.
Still further, trainmen have been injured in train yards even with two trainmen attempting to place a knuckle in an operative position in a coupling head of a drawbar, because the knuckles are not only heavy but also cumbersome and difficult to maneuver with respect to the coupling head.
Hence, there is a need for an improved apparatus and method for moving, lifting or maneuvering a knuckle into an operative position within the coupling head of a drawbar, not only to avoid injury to a trainman attempting to replace a knuckle in the field but also to facilitate the placement of a knuckle in an operative position in a drawbar at the railroad yard.